1. Field of the Invention
The present invention concerns an input keyboard for an electronic appliance in entertainment electronics.
2. Description of the Prior Art
It is becoming ever more common for the appliances of entertainment electronics to comprise input keyboards for either local control in the appliance itself or for remote control in a remote control device, where the base of the said keyboard is constituted by a circuit board with printed switch contacts. This design of an input keyboard facilitates the manufacture of input keyboards of this type and lowers their production costs. An input keyboard of this type for a remote control transmitter is known, for example, from the German periodical rme, 1980, No. 11, pages 311 to 315. This known remote control transmitter contains contacts for several pushbutton switches of the remote control transmitter, the said contacts being situated on a printed circuit board in copper-carbon technique, and a contact rubber mat laid between the circuit board and the pushbuttons, which are guided by openings in the cover plate of the remote control transmitter. At the positions corresponding to the various pushbuttons of the remote control transmitter, rubber domes are formed in the contact mat to act as spring elements. These rubber domes produce a snap effect upon depression of the pushbutton and contain a carbon contact that is vulcanized into the side that faces the contacts on the circuit board.
In many cases such input keyboards have to be used not only for choosing or setting functions, but also for changing values. It is becoming more and more common for such value adjustments to be brought about by electronic devices, for example by means of electronic selectors whose modulation rate can be set according to the position of the selector, or by means of trigger thresholds where the threshold value can be adjusted.